Method of reaming



Patented Sept. 3, 1946 UNITED STATES GFFICE METHOD OF REAMING Edgar L. Zehrbach, Lima, Ollio Application October 7, 1943, Serial No. 505,284

(Cl'. 'f7-72) 2 Claims.

This invention relates to reamers and particularly to reamers used in high precision Work.

An object is to produce a new and improved method of reaming by which the position yof the tool is adjusted in a simple and convenient manner to control the size of the hole. This is particularly important not only to secure accurate results but also to increase the life of the reamer, it being possible to slightly adjustthe reamer after it has been worn to such point that it cannot ream a hole of the desired diameter, so that it will thereafter ream. to the desired accuracy in spite ci wear. "This accomplishes a two-fold result. The life of the` reamer is greatly lengthened and also accurate reaming can be effected at all times.

Another object is to produce a simple and efficientv method for reaming relatively small holes with greater uniform accuracy than has been possible heretofore.l

A further object-is to produce a reaming method which militates against the formation of the socalled bell mouth at one Or opposite ends of the reamed hole.

A still further object is to produce a new and improved method of reaming holes of any predetermined size within the range of the reamer without changing in any way the form, configuration or structure of the tool itself but by a simplev l diameter.

adjustment or alteration of the position of the Y reamer Vrelative to the work.

O ther objects and advantages `of the invention will hereinafter appear, and for purposes of illustration but not of limitation, an embodiment of the invention is shown on the accompanying drawing in which` Figure lis a bottom plan view partly in section showing a lathe mounted reamer holder and reamer, with the latter axially aligned with the hole in the work;

Figure 2 is a top plan View of the parts shown in Figure 1, but with the reamer adjusted to'a position with its axis offset from or angularly disposed relative to the axis of the hole to be reamed;

Figure 3 is aV view substantially on the line 3 3 of Figure 1;

Figure 4 is a section substantially on the line 4-4 of Figure 2; and

Figure 5 is an enlarged fragmentary sectional View illustrating the operation of the reamer when the same is disposed with the reamer axis eccentric to the axis of the hole to be reamed.

The illustrated embodiment of the invention comprises a reamer A carried by a holder B, the latter being suitably mounted on a lathe. The

work W is formedv with a hole H to be reaxned. As will be readily understood, rotary motion is imparted to the work W during the reaming operation during which relative, translatory movement between' the holder B and work is imparted. r"I'he reamer has a shank portion Ill', a portion of thelforward end of which is fiuted as indicated at I I to carry away the cuttings in the usual manner. n advance of the fiuted portion II and in `fixed relation thereto, is a cutting head I2 formed with a suitable number of lands I3 arranged in annular formation. Directly in rear of the lands I3 is an inwardly tapered neck I4 merging with the flutedportion I I. y 4

An important feature of the invention is in the relatively narrow cutting head in rea-r of which is a shank portion of substantially reduced The length of the cutting head may vary in accordance with the length of the hole toI be reamed, the controlling factor being that the angularity or eccentricity of the reamer relative to the axis of the hole to be reamed must in no case be such that the shank or fluted portion of the reamer will engage the mouth or edge Dortion of the hole. In other words, with the parts in the position-shown in Figure 2, the reamer must be enabled to pass completely through the hole H without the ilu'ted portion II or Shank' `I Il engaging the mouth of the hole or that end ofthe hole in lwhich the reamer is inserted. The reamer shank may be cut away on one side to give a greater angular adjustment if circumstances make this necessary.

In operation itwill be manifest thatthe' reamer A can be moved in axial alignment with the hole H as indicated in Figure 1 to effect the desired reaming operation. Oftentimes it is not possible to Obtain exact axial alignment. This oftentimes is due to the lathe or other machine on which the reameris mounted because of Wear or inaccuracies in the machine. In such cases, when the ordinary reamer is employed, bell-mouthed holes result and particularly in precision Work, this is most objectionable, and results in the scrapping of that part. Bell-mouthed holes can not be reamed with the above described reamer A because even with the reamer A arranged out of axial alignment' or eccentrically with respect to the hole to be reamed, there is no possibility of bell-mouthing in View of the vshortness of the lands compared with the depth of the hole and the reduced diameter of the shank.

It is found empirically that such eccentricity of the reamer with respect to the axis of the hole to be reamed can be employed to greater advantage in the use of the reamer above described. With the reamer disposed in the position such as indicated on Figures 2 and 5, the cutting action is conned to the areas C and C or what might be termed the toe or front upper portion of the cutting lands and the heel or lower rearward portion (Figure 5). It Will be manifest that by varying the eccentricity or the oifset angular relation of -the reamer with respect to the axis of the hole to be reamed, the size of the reamed hole can be be varied. The amount of adjustment or eccentricity is governed by the amount of angularity which can be imposed on the reamer without its shank engaging the sides of the hole.

In practice this reamer may first be used in axial alignment with the hole to be reamed. After a period of time, the reamer becomes worn and the normal procedure so far as other reamers are concerned, is to discard it. In this case, continued use of the reamer can be had by angularly adjusting it as above mentioned so that the cutting head does not enter the hole axially but eccentrically. By the usev of plug gauges, the workmen can readily determine whether the hole is being reamed under size. In that event, adjustment is made of the reamer an amount suicient to compensate for the wear. Later on when iurther wear occurs and the gauge shows that the hole is again under size, a further angular adjustment of the reamer is eiected and its use continued. It is found that such reamer can be used over an extended period of time in an exceedingly satisfactory manner without sacrifice to accuracy of the reamed hole.

The holder B is designed to enable such angular adjustment of the reamer to be readily and conveniently eiiected. As shown, the holder has an outwardly extending barrel or chuck I5 into which the inner end of the shank I lits loosely. At the rear end of the barrel is a sleeve I6 which receives the inner end of the shank I 0. A pair of angularly disposed adjusting screws II arranged on the under side of the barrel are adapted to engage the shank I0 which rests against them by gravity. The inner end of the barrel I is xed to a plate I8 which abuts against a plate I9 suitably xed to the lathe. The plate I8 is pivotally mounted with respect to the plate I9 by a bolt 20 arranged at one side. The bolt 20 has a head 2I socketed to receive a wrench so that the plates can be loosened sufficiently to eiect the desired adjustment. On the other side of the barrel I5 the plates are connected by a bolt 22 which has an eccentric portion 23 disposed within an elongate slot 24 in the plate I8. Fixed to the outer end of the bolt 22 is a dial 25 formed with a socket 4.A 26 to receive suitable socket Wrench. On the rear side of the plate I9 is a nut 2'I. The dial 25 is provided with suitable calibrations 28 which may be brought into registration with a suitable mark formed on the plate I8 adjacent thereto.

In practice a plug gauge will show the size of the holes being reamed. If it appears that the holes are too small, then it is necessary that angular adjustment of the reamer A be made. This is effected by rst loosening the bolt 20 and then loosening the nut 21. Thereupon by the use of a socket wrench, the dial 25 can be adjusted to the desired extent. For example, it may appear that the reamed holes are one one-thousandth of an inch under size. In that event, the workman will know that by adjusting the dial the proper amount, the holes subsequently reamed will be one one-thousandth of an inch larger. Thereupon, by tightening the nut 21 and bolt 2I, the reaming operation can be continued. A pin 29 in the plate I8 secures the reamer in place.

Although I have shown and described an embodiment of the invention in connection with a lathe, it is to be understood that the invention can be embodied satisfactorily in a drill press where the reamer instead of the Work rotates, the work remaining stationary. It is therefore to be understood that changes in details of construction, arrangement and operation may be eiected without departing from the spirit of the invention especially as dened in the appended claims.

What I claim is:

l. The method of reaming which consists in providing a reamer with a cutting head of substantially less length than the depth of the hole to be reamed and of less diameter than the diameter of such hole,r olsetting angularly the axis of the reamer relative to the axis of the hole an amount predetermined according to the desired size of the reamed hole, and imparting relative translatory and rotary movements between the reamer and the work with the cutting head in such offset position.

2. The method of reaming which consists in providing a reamer with a cutting head of less diameter than the diameter of the hole to be reamed and a reduced operating shank, angularly offsetting the axis of the cutting head with respect to the axis of the hole an amount predetermined according to the desired sizeof the reamed hole and without the shank engaging the sides of the hole during the remaining operation, and imparting relative translatory and rotary movements between the reamer and the Work with the cutting head in such offset position,

EDGAR L. ZEHRBACH. 

